Revert "xds: Disable LOGICAL_DNS in XdsDepMan until used"

This reverts commit d374b26 as part of
reverting 297ab05.

Author: ejona86

xds/src/main/java/io/grpc/xds/XdsDependencyManager.java

@@ -82,9 +82,6 @@ private enum TrackedWatcherTypeEnum {
   private static final Locality LOGICAL_DNS_CLUSTER_LOCALITY = Locality.create("", "", "");
 
   private static final int MAX_CLUSTER_RECURSION_DEPTH = 16; // Specified by gRFC A37
-
-  static boolean enableLogicalDns = false;
-
   private final String listenerName;
   private final XdsClient xdsClient;
   private final SynchronizationContext syncContext;
@@ -366,14 +363,9 @@ private static void addConfigForCluster(
         }
         break;
       case LOGICAL_DNS:
-        if (enableLogicalDns) {
-          TrackedWatcher<List<EquivalentAddressGroup>> dnsWatcher =
-              tracer.getWatcher(DNS_TYPE, cdsUpdate.dnsHostName());
-          child = new EndpointConfig(dnsToEdsUpdate(dnsWatcher.getData(), cdsUpdate.dnsHostName()));
-        } else {
-          child = new EndpointConfig(StatusOr.fromStatus(
-              Status.INTERNAL.withDescription("Logical DNS in dependency manager unsupported")));
-        }
+        TrackedWatcher<List<EquivalentAddressGroup>> dnsWatcher =
+            tracer.getWatcher(DNS_TYPE, cdsUpdate.dnsHostName());
+        child = new EndpointConfig(dnsToEdsUpdate(dnsWatcher.getData(), cdsUpdate.dnsHostName()));
         break;
       default:
         child = new EndpointConfig(StatusOr.fromStatus(Status.UNAVAILABLE.withDescription(
@@ -814,9 +806,7 @@ public void subscribeToChildren(XdsClusterResource.CdsUpdate update) {
           addEdsWatcher(getEdsServiceName());
           break;
         case LOGICAL_DNS:
-          if (enableLogicalDns) {
-            addDnsWatcher(update.dnsHostName());
-          }
+          addDnsWatcher(update.dnsHostName());
           break;
         case AGGREGATE:
           update.prioritizedClusterNames()

xds/src/test/java/io/grpc/xds/XdsDependencyManagerTest.java

@@ -152,7 +152,6 @@ public class XdsDependencyManagerTest {
 
   private XdsDependencyManager xdsDependencyManager = new XdsDependencyManager(
       xdsClient, syncContext, serverName, serverName, nameResolverArgs);
-  private boolean savedEnableLogicalDns;
 
   @Before
   public void setUp() throws Exception {
@@ -169,8 +168,6 @@ public void setUp() throws Exception {
     testWatcher = new TestWatcher();
     xdsConfigWatcher = mock(TestWatcher.class, delegatesTo(testWatcher));
     defaultXdsConfig = XdsTestUtils.getDefaultXdsConfig(serverName);
-
-    savedEnableLogicalDns = XdsDependencyManager.enableLogicalDns;
   }
 
   @After
@@ -183,8 +180,6 @@ public void tearDown() throws InterruptedException {
     assertThat(adsEnded.get()).isTrue();
     assertThat(lrsEnded.get()).isTrue();
     assertThat(fakeClock.getPendingTasks()).isEmpty();
-
-    XdsDependencyManager.enableLogicalDns = savedEnableLogicalDns;
   }
 
   @Test
@@ -754,7 +749,6 @@ public void testChangeAggCluster() {
 
   @Test
   public void testLogicalDns_success() {
-    XdsDependencyManager.enableLogicalDns = true;
     FakeSocketAddress fakeAddress = new FakeSocketAddress();
     nameResolverRegistry.register(new FakeNameResolverProvider(
         "dns:///dns.example.com:1111", fakeAddress));
@@ -795,7 +789,6 @@ public void testLogicalDns_success() {
 
   @Test
   public void testLogicalDns_noDnsNr() {
-    XdsDependencyManager.enableLogicalDns = true;
     Cluster cluster = Cluster.newBuilder()
         .setName(CLUSTER_NAME)
         .setType(Cluster.DiscoveryType.LOGICAL_DNS)